Boy, this brings back memories!  Several years ago I put a hightop on my
'68 and you couldn't take a curve over 35 mph without feeling like it
was going to topple over.  I put a huge 3/4" sway bar with urethane
bushings on the rear, and I think a smaller 5/8" on the front.  It was
phenomenal what an improvement this made, but the drum brakes still
sucked and I finally got rid of it in favor of the Vanagon Westy I have
now.

A rear bar would definitely flatten out the lean on curves, it just
comes down to whether it's worth the cost.
--
Stuart MacMillan
Seattle

'84 Vanagon Westfalia w/2.1
'65 MGB (Daily driver since 1969)
'74 MGB GT (Restoring sloooowly)

Assisting on Restoration (and spending OPM):
'72 MGB GT (Daughter's)
'64 MGB (Son's)

Stripped and gone but their parts live on:
'68 MGB, '73 MGB, '67 MGB GT